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C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator whereas Si is intrinsic semiconductor. This is because
A
The four bonding electrons in the case of C lie in the third orbit, whereas for Si they lie in the fourth orbit
B
In case of C the valence band is not completely filled at absolute zero temperature
C
In case of C the conduction band is partly filled even at absolute zero temperature
D
The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Detailed Solution
Carbon: $1s^22s^22p^2$ — the four bonding electrons are in the second orbit. Silicon: $1s^22s^22p^63s^23p^2$ — they are in the third orbit.
Electrons in the third orbit are farther from the nucleus and less tightly bound, so the energy needed to free them (the band gap) is much smaller for Si (about 1.1 eV) than for C (about 5.4 eV).
So C is an insulator while Si is an intrinsic semiconductor.
Electrons in the third orbit are farther from the nucleus and less tightly bound, so the energy needed to free them (the band gap) is much smaller for Si (about 1.1 eV) than for C (about 5.4 eV).
So C is an insulator while Si is an intrinsic semiconductor.